9000 L4-2290cc 2.3L DOHC Turbo EFI (1992)
Throttle Position Sensor: Technical Service Bulletins
Throttle Potentiometer - Fault Code Testing Procedure
CATEGORY: Engine
SECTION: 2
PAGE: 27
ISSUE: 03/93-0311
CODE: 240
Subject:
Throttle Potentiometer Faults
(LH 2.4.2 with Electronic Throttle System)
Application:
1992 9000 Turbo
9000 models with Traction Control have a throttle potentiometer integrated into the throttle housing. This throttle potentiometer sends a signal to the
Electronic Throttle System (ETS) control module. The ETS control module then creates a digital throttle position communication signal. This digital
throttle position signal is sent from pin # 26 of the ETS control module to pin # 3 of the LH control module. The ETS control module changes the
duration of the pulsed square wave as the throttle position changes.
Should a fault occur in the throttle potentiometer or ETS control module, Fault Code 25771 may be stored in the LH ECM. This bulletin covers the fault
tracing procedure for LH Fault Code 25771 on ETS-equipped vehicles.
Cars Affected:
1992 9000 Turbo models
Action:
1.
Check that there are no fault codes stored in the ETS system. Many ETS faults could cause an incorrect throttle position digital signal to be
received at LH ECM pin # 3.
2.
With all components connected, and the engine running, connect an oscilloscope or a Logic Probe (Figure 1) to LH ECM pin # 3.
^
With the throttle closed, you should find a square wave with a short "HI" logic level (green LED much brighter than the red one) and a long
duration "LO" logic level. (See Figure 2.)
CAUTION:
BE SURE THE PARKING BRAKE IS SET, THE WHEELS ARE BLOCKED AND THE PATH IN FRONT OF THE VEHICLE IS CLEAR.